Automatic splitter and governor control for manually shifted transmission

ABSTRACT

A system and method for completing an automatic up-shift during an engine progressive governor event in a controller-assisted, manually shifted compound transmission system ( 10 ) and splitter shift control therefor. Auxiliary splitter section ( 16 B) shifts are automatically implemented by a splitter shifter ( 28 ) under commands ( 56 ) from a controller ( 48 ). The controller ( 48 ) overrides the engine governor control and controls engine torque to approach, and preferably reach a zero torque condition and bring the transmission to a splitter-neutral condition to enable an automatic up-shift when the splitter button has been selected or lever shift has been moved by the operator. Depending on the type of shift event, the transmission will automatically complete the upshift or the operator can manually complete the upshift after engine synchronization. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to automatic splitter shifting in amanually shifted compound transmission having a lever-shifted mainsection connected in series with an auxiliary splitter orsplitter-and-range section. In particular, the present invention relatesto a splitter control for transmissions of the type described forautomatically implementing splitter up-shifts and/or splitter-and-rangeshifts during a manual lever shift when an engine governor event isencountered.

2. Description of the Related Art

Controller-assisted, manually shifted transmission systems are known inthe prior art, as may be seen by reference to U.S. Pat. Nos. 5,582,558;5,755,639; 5,766,111; 5,791,189; 5,974,906; 5,989,155 and 6,015,366, thedisclosures of which are incorporated herein by reference.

Compound transmissions having a range and/or combined range- andsplitter-type auxiliary transmission section are well known in the priorart, as may be seen by reference to U.S. Pat. Nos. 4,754,665 and5,390,561, the disclosures of which are incorporated herein byreference.

Transmissions having manually shifted main sections and automaticallyshifted splitter sections are known in the prior art, as may be seen byreference to U.S. Pat. Nos. 5,435,212; 5,938,711; 6,007,455 and6,044,721, the disclosures of which are incorporated herein byreference.

Compound transmissions having automatically implemented range shiftingare well known in the prior art, as may be seen by reference to U.S.Pat. Nos. 5,911,787 and 5,974,906, the disclosures of which areincorporated herein by reference.

One technique for controlling engine fueling to thereby limit enginespeed during manual gear shifting operations is commonly referred to asprogressive shift governor control, as may be seen by reference to U.S.Pat No. 6,135,918, the disclosure of which is incorporated herein byreference. In progressive shift governor control, a linear engine speedlimit, or governed engine speed limit, is typically established byspecifying a first engine speed limit RPM1 at a first vehicle speed VS1,and a second engine speed limit RPM2 at a second vehicle speed VS2. Thegoverned engine speed limit linearly increases from RPM1 to RPM2 betweenVS1 and VS2 and is held constant at RPM2 beyond VS2, wherein RPM2 istypically less than rated engine speed. Rated engine speed is definedfor purposes of the present invention as the engine speed at which theengine produces an advertised horsepower value.

The purpose of progressive shift governor control is to graduallyincrease available engine speed (and thus more engine power) as vehiclespeed increases between VS1 and VS2, wherein typical values for VS1 andVS2 are 0.0 and 40 mph, respectively. This engine speed limiting schemeaccordingly encourages the vehicle operator to manually shift gears atlower engine speeds than may otherwise occur, particularly in the lowertransmission gears, thereby resulting in fuel savings associated withmore efficient engine operation.

While the progressive shift governor control feature achieves the goalof encouraging vehicle operators to shift at lower engine speeds, it hascertain drawbacks associated therewith. For example, when descending agrade or when hauling a heavily loaded trailer on level ground,providing a hard limit on available engine speed can hinder thedrivability of the vehicle. One example of such hindered drivability mayoccur when attempting an automatic up-shift during an engine progressiveshift governor event when descending a downhill grade, or moving atspeed on level ground in a heavily loaded condition under low throttle,hereinafter characterized as a coasting condition or coasting. When inthe coasting condition, the engine is being forced by the inertia of thevehicle to rotate at a higher speed than is commanded by the enginecontroller. Under the control of the progressive shift governor control,the governed engine speed limit may cause the vehicle to enter into acoasting condition in which the vehicle is driving the engine at a speedgreater than that permitted by the progressive shift governor control,irrespective of the throttle position, resulting in a negative drivelinetorque. If the operator attempts to select the next higher gear bydepressing the splitter button under such a negative torque condition,it may not be possible to shift gears due to the negative torque. As aresult, the operator may be forced to break torque by depressing theclutch so that the transmission may be shifted to splitter-neutral andthen to splitter high for the desired up-shift, thereby overcoming muchof the benefit of an automated shift.

SUMMARY OF THE INVENTION

In accordance with the present invention, a manually shifted compoundtransmission with a splitter or combined splitter-and-range auxiliarysection is provided, which will automatically shift the splitter sectionand/or automatically disengage and then reengage the splitter section aslong as the lever position does not change. Logic rules are provided todetermine when the splitter should be reengaged after the splitter isshifted to neutral.

The foregoing is accomplished in a manually shifted compoundtransmission having a lever-shifted main section connected in serieswith a splitter or combined splitter-and-range auxiliary section havingan actuator for automatically implementing controller-initiated splittershifts by sensing vehicle operating conditions.

Accordingly, one aspect of the present invention is to provide a methodfor controlling splitter shifting in a controller-assisted, manuallyshifted vehicular transmission system. The method comprises the steps ofsensing if an upshift target gear ratio was selected prior to activationof engine governor control, determining a type of shift event, and ifthe sensing step is satisfied, controlling one of an engine speed and anengine torque to produce a zero torque condition and place the splitterauxiliary section in a splitter-neutral condition.

Another aspect of the present invention is to provide a method forcontrolling splitter shifting in a controller-assisted, manually shiftedvehicular transmission system. The method comprises the steps of sensingif an upshift target gear ratio was selected prior to activation ofengine governor control, determining a type of shift event, andoverriding the engine governor control to produce a zero torquecondition when said sensing step is satisfied, thereby placing thesplitter auxiliary section in a splitter-neutral condition.

Yet another aspect of the present invention is to provide a new andimproved splitter shift control for manually shifted compoundtransmissions having a splitter shifter for automatically implementingsplitter shifts, wherein a controller includes logic rules for:

-   -   sensing if an upshift target gear ratio was selected prior to        activation of engine governor control;    -   determining a type of shift event; and    -   controlling one of an engine speed and an engine torque to        produce a zero torque condition and place the splitter auxiliary        section in a splitter-neutral condition when the upshift target        gear ratio is selected prior to activation of engine governor        control.

These and other aspects of the present invention will become apparentfrom a reading of the following description of the preferred embodimenttaken in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic illustration of an ECU-assisted compoundmechanical transmission system advantageously utilizing the rangeshifting control of the present invention.

FIG. 2 is a chart illustrating the shift pattern and representativenumerical ratios for the transmission of FIG. 1.

FIG. 3 is a schematic illustration of the structure of the compoundmechanical transmission of FIG. 1.

FIG. 4 is a schematic illustration of a three-position splitter actuatorfor use with the transmission system of FIG. 1.

FIGS. 5A and 5B are schematic illustrations of a shift shaft positionsensor mechanism for use in the system of FIG. 1.

FIG. 6 is a schematic illustration, in flow chart format, of thesplitter and governor control according to one aspect of the presentinvention.

FIG. 7 is a schematic illustration, in flow chart format, of thesplitter and governor control according to another aspect of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A computer-assisted (i.e., microprocessor-based, controller-assisted)vehicular compound mechanical transmission system 10, particularly wellsuited to utilize the range shift control of the present invention, maybe seen by reference to FIGS. 1-5B.

System 10 is of the type commonly utilized in heavy-duty vehicles, suchas the conventional tractors of tractor/semi-trailer vehicles, andincludes an engine, typically a diesel engine 12, a master frictionclutch 14 contained within a clutch housing, a multiple-speed compoundtransmission 16, and a drive axle assembly (not shown). The transmission16 includes an output shaft 20 drivingly coupled to a vehicle driveshaft 22 by a universal joint 24 for driving the drive axle assembly.The transmission 16 is housed within a transmission housing to which isdirectly mounted the shift tower of the shift lever assembly 30. Thepresent system is equally applicable to remotely mounted shift levers,as are used in cab-over-engine types of vehicles.

FIG. 2 illustrates a shift pattern for assisted manual shifting of acombined range-and-splitter-type compound transmission shifted by amanually operated shift lever. Briefly, the shift lever 31 is movable inthe side-to-side or X—X direction to select a particular ratio or ratiosto be engaged and is movable in the fore and aft or Y—Y direction toselectively engage and disengage the various ratios. The shift patternmay include an automatic range shifting feature and automaticallyselected and/or implemented splitter shifting, as is known in the priorart. Manual transmissions utilizing shift mechanisms and shift patternsof this type are well known in the prior art and may be appreciated ingreater detail by reference to aforementioned U.S. Pat. Nos. 5,000,060and 5,390,561.

Typically, the shift lever assembly 30 will include a shift finger orthe like (not shown) extending downwardly into a shifting mechanism 32,such as a multiple-rail shift bar housing assembly or a single shiftshaft assembly, as is well known in the prior art and as is illustratedin aforementioned U.S. Pat. Nos. 4,455,883; 4,550,627; 4,920,815 and5,272,931.

In the automatic range shifting feature, as the shift lever moves in thetransition area between the middle leg (3/4-5/6) and the righthand leg(7/8-9/10) of the shift pattern, it will cross a point, AR, which willactuate a mechanical or electrical range switch, or will be sensed by aposition sensor, to cause automatic implementation of a range shift.

The present invention also is applicable to transmission systems of thetype utilizing range shift selector switches which are manually operatedindependent of shift lever position, as illustrated in aforementionedU.S. Pat. No. 5,222,404.

Shifting of transmission 16, comprising main section 16A coupled inseries to auxiliary section 16B, is semi-automaticallyimplemented/assisted by the vehicular transmission system 10,illustrated in FIGS. 1-5B. Main section 16A includes an input shaft 26,which is operatively coupled to the drive or crank shaft 28 of thevehicle engine 12 by master clutch 14, and output shaft 20 of auxiliarysection 16B is operatively coupled, commonly by means of a drive shaft24, to the drive wheels of the vehicle. The auxiliary section 16B is asplitter type, preferably a combined range-and-splitter type, asillustrated in U.S. Pat. Nos. 4,754,665 and 5,390,561.

The change-gear ratios available from main transmission section 16 aremanually selectable by manually positioning the shift lever 31 accordingto the shift pattern prescribed to engage the particular desired changegear ratio of main section 16A.

The system may include sensors 30 (for sensing engine rotational speed(ES)), 32 (for sensing input shaft rotational speed (IS)), and 34 (forsensing output shaft rotational speed (OS)), and providing signalsindicative thereof. As is known, with the clutch 14 (i.e., no slip)engaged and the transmission engaged in a known gear ratio, ES=IS=OS*GR(see U.S. Pat. No. 4,361,060). Accordingly, if clutch 14 is engaged,engine speed and input shaft speed may be considered as equal. Inputshaft speed sensor 32 may be eliminated and engine speed (ES), as sensedby a sensor or over a data link (DL), substituted therefor.

Engine 12 is electronically controlled, including an electroniccontroller 36 communicating over an electronic data link (DL) operatingunder an industry standard protocol such as SAE J-1922, SAE J-1939, ISO11898 or the like. Throttle position (operator demand) is a desirableparameter for selecting shifting points and in other control logic. Aseparate throttle position sensor 38 may be provided or throttleposition (THL) may be sensed from the data link. Gross engine torque(T_(EG)) and base engine friction torque (T_(BEF)) also are available onthe data link.

A manual clutch pedal 40 controls the master clutch 14, and a sensor 42provides a signal (CL) indicative of clutch-engaged or -disengagedcondition. The condition of the clutch also may be determined bycomparing engine speed to input shaft speed if both signals areavailable. An auxiliary section actuator 44 including a range shiftactuator and a splitter actuator 46 is provided for operating the rangeclutch and the splitter section clutch in accordance with command outputsignals from ECU 48. The shift lever 31 has a knob 50 which containssplitter selector switch 52 by which a driver's intent to initiate asplitter shift may be sensed.

System 10 may include a driver's display unit 54 including a graphicrepresentation of the six-position shift pattern with individuallylightable display elements 56, 58, 60, 62, 64 and 66, representing eachof the selectable engagement positions. Preferably, each half of theshift pattern display elements (i.e., 58A and 58B) will be individuallylightable, allowing the display to inform the driver of the lever andsplitter position for the engaged ratio.

The system includes a control unit or ECU 48, preferably amicroprocessor-based control unit of the type illustrated in U.S. Pat.Nos. 4,595,986; 4,361,065 and 5,335,566, the disclosures of which areincorporated herein by reference, for receiving input signals 68 andprocessing same according to predetermined logic rules to issue commandoutput signals 70 to system actuators, such as the splitter sectionactuator 46, the engine controller 36, the range shift actuator and/orthe display unit 54. A separate system controller may be utilized, orthe engine controller ECU 36 communicating over an electronic data linkmay be utilized.

As shown in U.S. Pat. Nos. 5,651,292 and 5,661,998 (the disclosures ofwhich are incorporated herein by reference), the splitter actuator 46is, preferably, a three-position device, allowing a selectable andmaintainable splitter section neutral. Alternatively, a “pseudo”splitter-neutral may be provided by deenergizing the splitter actuatorwhen the splitter clutch is in an intermediate, non-engaged position.

The structure of the 10-forward-speed combined range-and-splitter-typetransmission 16 is schematically illustrated in FIG. 3. Transmissions ofthis general type are disclosed in aforementioned U.S. Pat. Nos.5,000,060; 5,370,013 and 5,390,561.

Transmission 16 includes a main section 16A and an auxiliary section16B, both contained within a housing including a forward end wall 16C,which may be defined by the clutch housing, and a rearward end wall 16D,but (in this particular embodiment) not an intermediate wall.

Input shaft 26 carries input gear 76 fixed for rotation therewith anddefines a rearwardly opening pocket wherein a reduced diameter extensionof output shaft 20 is piloted. A non-friction bushing or the like may beprovided in the pocket or blind bore. The rearward end of input shaft 26is supported by bearing 78 in front end wall 16C, while the rearward endof output shaft 20 is supported by bearing assembly 80 in rear end wall16D.

The mainshaft 82, which carries mainshaft clutches 84 and 86, and themainshaft splitter clutch 88 is in the form of a generally tubular bodyhaving an externally splined outer surface and an axially extendingthrough bore for passage of output shaft 20. Shift forks 90 and 92 areprovided for shifting clutches 84 and 86, respectively (see FIG. 5A).Mainshaft 82 is independently rotatable relative to input shaft 26 andoutput shaft 20 and preferably is free for limited radial movementrelative thereto.

The main section 16A includes two substantially identical main sectioncountershaft assemblies 94, each comprising a main section countershaft96 carrying countershaft gear pairs 98, 102, 104 and 106 fixed thereto.Gear pairs 98, 102, 104 and 106 are constantly meshed with input gear76, mainshaft gears 108 and 110 and an idler gear (not shown), which ismeshed with reverse mainshaft gear 112, respectively. One of thecountershaft assemblies 94 may include a gear 100, commonly known as apower take-off gear.

Main section countershaft 96 extends rearwardly into the auxiliarysection, where its rearward end is supported directly or indirectly inrear housing end wall 16D.

The auxiliary section 16B of transmission 16 includes two substantiallyidentical auxiliary countershaft assemblies 114, each including anauxiliary countershaft 116 carrying auxiliary countershaft gears 118,120 and 122 for rotation therewith. Auxiliary countershaft gear pairs118, 120 and 122 are constantly meshed with splitter gear 124,splitter/range gear 126 and range gear 128, respectively. Splitterclutch 88 is fixed to mainshaft 82 for selectively clutching either gear124 or 126 thereto, while synchronized range clutch 130 is fixed tooutput shaft 20 for selectively clutching either gear 126 or gear 128thereto.

Auxiliary countershafts 116 are generally tubular in shape, defining athrough bore for receipt of the rearward extensions of the main sectioncountershafts 96. Bearings or bushings are provided to rotatably supportauxiliary countershaft 116 on main section countershaft 96.

The splitter jaw clutch 88 is a double-sided, non-synchronized clutchassembly which may be selectively positioned in the rightwardmost orleftwardmost positions for engaging either gear 126 or gear 124,respectively, to the mainshaft 82 or to an intermediate position whereinneither gear 124 or 126 is clutched to the main shaft. Splitter jawclutch 88 is axially positioned by means of a shift fork 98 controlledby a three-position actuator, such as a piston actuator, which isresponsive to a driver selection switch such as a button or the like onthe shift knob, as is known in the prior art and to control signals fromECU 48 (see U.S. Pat. No. 5,661,998). Two-position synchronized rangeclutch assembly 130 is a two-position clutch which may be selectivelypositioned in either the rightwardmost or leftwardmost positions thereoffor selectively clutching either gear 128 or 126, respectively, tooutput shaft 20. Clutch assembly 130 is positioned by means of a shiftfork (not shown) operated by means of a two-position piston device.Either piston actuator may be replaced by a functionally equivalentactuator, such as a ball screw mechanism, ball ramp mechanism or thelike.

By selectively axially positioning both the splitter clutch 88 and therange clutch 130 in the forward and rearward axial positions thereof,four distinct ratios of mainshaft rotation to output shaft rotation maybe provided. Accordingly, auxiliary transmission section 16B is athree-layer auxiliary section of the combined range and splitter typeproviding four selectable speeds or drive ratios between the input(mainshaft 82) and output (output shaft 20) thereof. The main section16A provides a reverse and three potentially selectable forward speeds.However, one of the selectable main section forward gear ratios, thelow-speed gear ratios associated with mainshaft gear 110, is notutilized in the high range. Thus, transmission 16 is properly designatedas a “(2+1)×(2×2)” type transmission providing nine or ten selectableforward speeds, depending upon the desirability and practicality ofsplitting the low gear ratio.

Splitter shifting of transmission 16 is accomplished responsive toinitiation by a vehicle operator-actuated splitter button 52 or thelike, usually a button located at the shift lever knob, while operationof the range clutch shifting assembly is an automatic response tomovement of the gear shift lever between the central and rightwardmostlegs of the shift pattern, as illustrated in FIG. 2. Alternatively,splitter shifting may be automated (see U.S. Pat. No. 5,435,212). Rangeshift devices of this general type are known in the prior art and may beseen by reference to aforementioned U.S. Pat. Nos. 3,429,202; 4,455,883;4,561,325 and 4,663,725.

To protect the range synchronizers, a properly executed range shiftshould occur in the sequence of (i) disengaging the main section byshifting to main section neutral, (ii) then initiating and completingthe range section shift, and (iii) then, after the range section shiftis completed, engaging the main section in the appropriate ratio.

As is known in the prior art, range clutch damage, also called “rangesynchronizer burnout,” is most likely to occur in three situations: (i)if the main section is engaged prior to completion of a range up-shift,(ii) if the main section is engaged prior to completion of a rangedownshift, or (iii) if a range downshift is attempted at too high avehicle speed. As will be discussed below, the range shift control ofthe present invention is effective to minimize or eliminate damage undersuch occurrences and to allow rapid and dependable completion ofpermissible range shifts.

Although the present invention is illustrated in the embodiment of acompound transmission not having an intermediate wall, the presentinvention is equally applicable to transmissions of the type illustratedin aforementioned U.S. Pat. Nos. 4,754,665; 5,193,410 and 5,368,145.

According to the present invention, and as more fully described inaforementioned U.S. Pat. No. 5,651,292, the interengaging clutch teethprovided on splitter clutch 88 and on splitter gear 124 andsplitter/range gear 126 are of a relatively large backlash (i.e., about0.020-0.060 inches for a 3.6-inch pitch diameter clutch), which willassure that almost any attempted splitter shift under full force will becompleted.

The clutch 88 is moved by a shift fork 98 attached to the piston rod 140of the piston actuator assembly 142 (see FIG. 4). Actuator assembly 142may be a conventional three-position actuator (see U.S. Pat. No.5,054,591, the disclosure of which is incorporated herein by reference)or an actuator of the type illustrated in U.S. Pat. Nos. 5,682,790 or5,661,998 (the disclosures of which are incorporated herein byreference), wherein pulse width modulation of a selectively pressurizedand exhausted chamber 144 may be used to achieve the three splitterpositions (L, N, H) of the shift fork.

Preferably, the splitter clutch actuator 142 will be capable of applyinga variable force, such as by pulse width modulation, of supply pressure.A force lesser than full force may be utilized when disengaging and/orwhen synchronous conditions cannot be verified.

The controller 48 is provided with logic rules under which, if the mainsection is engaged, a shift from splitter neutral into a selected targetsplitter ratio is initiated such that, under normal conditions,including proper operator fuel control, the synchronous error (which isequal to input shaft rotational speed minus the product of output shaftrotational speed and transmission target gear ratio) is expected to beequal to or less than a value selected to give smooth, high-qualityshifts ((IS-(OS*GR))=ERROR≦REF). The timing is done in regard tosensed/expected shaft speeds, shaft acceleration/deceleration andactuator reaction times.

In certain situations, the logic rules will recognize operatingconditions wherein the preferred synchronous window (i.e., IS=(OS*GR)±60RPM) must be expanded to accomplish a splitter shift, even at theexpense of shift quality. These situations, usually associated withup-shifts, include if shifting attempted at low engine speeds whereinexpected engine speed at shift completion will be undesirably low, ifdeceleration of the output shaft is relatively high (dOS/dt<REF), if thedeceleration of the engine is relatively low (dES/dt>REF) and/or if theabsolute value of the synchronous error is not approaching the normalvalue at an acceptable rate.

The position of the shift lever 31 or of the shifting mechanism 32controlled thereby may be sensed by a position sensor device. Variouspositioning sensing assemblies are known in the prior art, with apreferred type illustrated in allowed U.S. Pat. No. 5,743,143, assignedto the assignee of this application, the disclosure of which isincorporated herein by reference.

Referring to FIGS. 5A and 5B, shifting mechanism 32 is illustrated as asingle shift shaft device 160 having a shaft 162 which is rotatable inresponse to X—X movements of shift lever 31 and axially movable inresponse to Y—Y movements of shift lever 31. Mechanisms of this type aredescribed in detail in aforementioned U.S. Pat. No. 4,920,815.

Shift shaft 162 carries the main section shift forks 90 and 92 forselective axial movement therewith and a shift block member 164 forreceiving a shift finger or the like. A pair of coils 166 and 168provides a pair of signals (collectively GR) indicative of the axial androtational position of shaft 162 and, thus, of shift lever 31 relativeto the shift pattern illustrated in FIG. 2. Preferably, the rate ofchange of position (dGR/dt) also may be determined and utilized toenhance shifting of the system 10.

By way of example, referring to FIG. 2, if shift lever position can besensed, the need for a fixed switch or the like at point AR to sense arequired initiation of a shift between low range and high range iseliminated. Further, as physical switches are no longer required, theshift pattern position at which a range shift will be commanded can bevaried, such as to points 180, 182 or 184, to enhance system performanceunder various operating conditions.

If in first (1st) through fourth (4th), a shift into high range isunlikely, and the auto range shift initiation point may be moved toposition 184 (away from the expected shift lever path) to preventinadvertent actuation of a range shift. If in sixth (6th) with a highengine speed, a shift into high range is likely and moving the autorange initiation point to position 180 will allow for a quickerinitiation of a range shift.

According to the present invention, the operator is allowed to controlengine fueling unless the current vehicle operating conditions indicatethat his/her operation of the throttle pedal will not allow the jawclutches associated with the current target ratio to engage. Ifoperating conditions, including operator setting of the throttle pedal,indicate that the operator will complete a splitter shift into targetratio, the engine will be fueled in accordance with operator throttlesetting. If not, automatic engine fueling may occur. If the splittersection does engage prior to the main section, as is preferred, theoperator will remain in complete control of engine fueling to completethe shift by engaging the main section.

The state of engagement (i.e., engaged or neutral) of the maintransmission section 16A is an important control parameter for system10. By way of example, if main section neutral is sensed, the splittermay be commanded to a full force engagement, regardless of the existenceor absence of appropriate synchronous conditions. Also, if the mainsection is engaged while the splitter is in neutral, the system will notcause splitter engagement until an appropriate substantial synchronouscondition is sensed and may then initiate automatic fuel control ifrequired. Of course, it is important to prevent or minimize falsedeterminations of main section neutral and/or engaged conditions.

Referring to FIG. 2, a first narrow band 202 and a second wider band 204of vertical displacements from a center position 200 are utilized todetermine if the main section is or is not in neutral. If thetransmission main section is not confirmed as being in main sectionneutral, the neutral confirmation band will be the narrower band 202.This will assure that the main section 16A is truly in neutral beforedeclaring a main section neutral condition. If the transmission mainsection 16A is confirmed as being in neutral, the neutral confirmationband will be the wider band 204. This assures that mere overshooting ofneutral or raking of main section jaw clutches will not be incorrectlyinterpreted as a main section engaged condition.

Sensing the shift lever at point 206 will always be interpreted as mainsection neutral, and sensing the shift lever at point 208 will always beinterpreted as main section engaged. However, if the shift lever issensed at point 210, this will not cause a previous determination of aneutral or engaged condition to change.

Vehicle operating conditions other than or in addition to currentlyengaged or neutral condition of the main section 16A may be used to varythe width of the neutral sensing bands.

In the prior art automated mechanical transmission systems, when it wasnecessary to significantly reduce engine speed to synchronize forengaging an up-shift target gear ratio, the engine was commanded bycontroller 48 to reduce driveline torque to enable a shift to neutral,and to subsequently bring the engine speed to a synchronous targetengine speed (ES=ES_(TARGET)). Certain engines of certain manufacturersalso implement an engine governor control of the engine speed, such as aprogressive shift engine governor control. The progressive shift enginegovernor control, in one embodiment, is stored or embedded in the formof logic steps within controller 36. The engine deceleration rate thatoccurs is dependent upon the engine manufacturer's implementation of itsspeed control mode and can sometimes be undesirably slow, as the speedcontrol mode attempts to smoothly ramp engine speed to the target enginespeed limit. “Ramped” is used to mean a modulated rate of decelerationless than the rate of unmodulated engine deceleration.

According to the present invention, Applicants have discovered that whena significant decrease in engine speed is required to execute aclutchless or float shift into an up-shift target gear ratio, and thevehicle is operating in a coasting condition, the progressive shiftgovernor control may prevent shifting. Shifting may be prevented iftransmission 16 is sustaining a torque load. The transmission willcommonly be sustaining a negative torque load in the coasting condition.This negative torque condition undesirably induces a force withintransmission 16 resisting a shift to neutral. To permit shifting thetransmission, the driver is required to break the engine torque,typically by using the master clutch 14. Alternatively, if the operatoris aware of the potential for the above-described condition, theoperator may elect to shift earlier in an attempt to complete aclutchless, automation-assisted shift. However, this attempt to shiftearly may result in a lower than desired engine speed.

According to one aspect of the invention, as shown in FIG. 6, a protocolfor controlling splitter shifting in a controller-assisted manuallyshifted vehicular transmission system 10 is described. The protocol, inone embodiment, is stored or embedded in the form of logic steps withinECU 48. The protocol begins at step 600, and at step 602, the enginegovernor control, such as a progressive shift engine governor control,is activated. Next, the control unit or ECU 48 determines whether asplitter shift is selected and an automatic up-shift is probable, andwhether a coasting condition is present in step 604. A splitter shift isselected when the operator depresses the splitter button. For example,the operator may select a splitter shift when shifting from first(1^(st)) to second (2^(nd)) to automatically perform a float shiftwithout using the master clutch 14. Whether an automatic up-shift isprobable depends on vehicle conditions, such as engine speed and vehiclespeed. For example, an up-shift is probable when the engine speed isnear maximum engine speed. A coasting condition exists when the vehicleis driving the engine, rather than the engine driving the vehicle,irrespective of the throttle position. If a splitter shift has not beenselected, or if neither an up-shift is probable, nor coasting ispresent, then the protocol proceeds to step 610 and standard shiftprotocols are invoked. The up-shift is completed in step 612, and theprotocol ends at step 614.

If the conditions of step 604 are satisfied, the protocol proceeds tostep 606 in which ECU 48 determines whether the shift initiationindicators are true, that is the indicators are consistent with theconditions appropriate for shifting, such as the splitter button beingdepressed, the throttle pedal is no longer being depressed by theoperator, or the like. If not, then the protocol proceeds to steps 610,612 and 614. If so, then the protocol proceeds to step 608 in which thetransmission controller 48 overrides the engine governor control andincreases engine torque such that the engine torque approaches, andpreferably reaches a zero torque condition to enable the splitterauxiliary section to be shifted to a splitter-neutral condition requiredfor the operator to engage an up-shift target gear ratio. By definition,increasing the engine torque is to overcome the negative torquecondition of the transmission 16 by controlling the engine to reduce anabsolute magnitude of torque sustained by the transmission. Ideally, thetorque magnitude approaches, and preferably reaches zero.

In the coasting condition, the engine may be tending to slow down thevehicle and the engine speed may increase when the absolute magnitude ofengine torque moves toward the engine zero torque condition. Forexample, to increase engine torque and/or engine speed, the controller54 may send a message through the data link DL (FIG. 1) to send acontrolled amount of fuel to the engine 12. Once the engine zero torquecondition is reached, the established shift protocol in step 610 can beused to engage an up-shift target gear ratio in step 612. The protocolthen ends in step 614.

According to another aspect of the invention, as shown in FIG. 7, analternative protocol for controlling splitter shifting in acontroller-assisted manually shifted vehicular transmission system 10 isdescribed. The protocol begins at step 700. At step 702, the enginegovernor control, such as a progressive shift engine governor control,is activated. Next, a determination is made as to whether the operatorhas selected an up-shift by the position of the splitter button in step704. If not, then the protocol proceeds to step 722 and ends at step716. If so, then a determination is made as to whether the up-shift wasselected prior to the activation of the governor control in step 706. Ifnot, then the protocol proceeds to step 720 and determines whether theshift initiation indicators are true, similar to step 606 of FIG. 6. Ifso, the controller 48 overrides the governor control and increasesengine torque such that the engine torque approaches, and preferablyreaches a zero torque condition to enable the splitter auxiliary sectionto be shifted to a splitter-neutral condition required for the operatorto engage an up-shift target gear ratio in step 710, similar to step 608of FIG. 6. If the determination is made in step 720 that the shiftinitiation indicators are false, then the protocol proceeds to step 722and the transmission system 10 does not override the governor controland exits in step 716.

If in step 706 a determination was made that up-shift was selected priorto the activation of the governor control, then the protocol proceeds tostep 708 and a determination is made whether the operator has selectedan automatic up-shift by depressing the splitter button to shift from,for example, first (1^(st)) to second (2^(nd)), and perform a floatshift without using the master clutch 14. If so, then the protocolproceeds to steps 710 through 716. If not, then a determination is madein step 718 whether the operator has selected a manual compound shift. Amanual compound shift occurs when the operator moves the shift lever,for example, from second (2^(nd)) to third (3^(rd)). If not, then theprotocol proceeds to step 720 for a determination of whether the shiftinitiation indicators are true. If so, then the protocol proceeds tostep 710 and the controller 48 overrides the governor control andincreases engine torque such that the engine torque approaches, andpreferably reaches a zero torque condition to enable the splitterauxiliary section to be shifted to a splitter-neutral condition requiredfor the operator to engage an up-shift target gear ratio. Then, theprotocol proceeds to step 712 through 716, similar to steps 610 through614 of FIG. 6.

As can be seen with both aspects of the invention described in FIGS. 6and 7, the transmission system 10 temporarily overrides the enginegovernor control, for example, a progressive shift governor control, andincreases engine torque such that the engine torque approaches, andpreferably reaches a zero torque condition to enable the splitterauxiliary section to be shifted to a splitter-neutral condition requiredfor the operator to engage an up-shift target gear ratio. Thisoverriding feature can be accomplished, for example, by the controller48 sending a message through the data link DL to send a controlledamount of fuel to the engine 12, thereby temporarily overriding theengine governor control. Once the zero torque condition is reached, anestablished shift protocol can be used to engage the up-shift targetgear ratio.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation, and the scope of theappended claims should be construed as broadly as the prior art willpermit.

1. A method for controlling splitter shifting in a controller-assisted,manually shifted vehicular transmission system having a splitterauxiliary section, said method comprising the steps: sensing if anupshift target gear ratio was selected prior to activation of an enginegovernor control; determining a type of shift event; and controlling oneof an engine speed and an engine torque to produce a zero torquecondition and place the splitter auxiliary section in a splitter-neutralcondition in response to a positive sensing that an upshift target gearratio was selected prior to activation of the engine governor control.2. The method of claim 1, wherein the zero torque condition is producedby controlling a supply of fuel to an engine to increase one of theengine speed and the engine torque.
 3. The method of claim 1, whereinsaid controlling step is performed by overriding the engine governorcontrol.
 4. The method of claim 1, further including the step ofcommanding the splitter auxiliary section to be automatically engaged inthe upshift target gear ratio when the type of shift event comprises asplitter upshift event.
 5. The method of claim 1, further including thestep of commanding the splitter auxiliary section to be manually engagedin the upshift target gear ratio when the type of shift event comprisesa compound upshift event.
 6. A method for controlling splitter shiftingin a controller-assisted, manually shifted vehicular transmission systemhaving a splitter auxiliary section, said method comprising the steps:sensing if the upshift target gear ratio was selected prior toactivation of an engine governor control; determining a type of shiftevent; and overriding the engine governor control to produce a zerotorque condition in response to said sensing step being satisfied,thereby placing the splitter auxiliary section in a splitter-neutralcondition.
 7. The method of claim 6, wherein the zero torque conditionis produced by controlling a supply of fuel to an engine to increase oneof the engine speed and the engine torque.
 8. The method of claim 6,further including the step of commanding the splitter auxiliary sectionto be automatically engaged in the upshift target gear ratio when thetype of shift event comprises a splitter upshift event.
 9. The method ofclaim 6, further including the step of permitting the splitter auxiliarysection to be manually engaged in the upshift target gear ratio when thetype of shift event comprises a compound upshift event.
 10. Acontroller-assisted, manually shifted vehicular transmission systemcomprising an internal combustion engine driving an input shaft of acompound transmission having a multiple-ratio main section shifted by ashift lever manually movable in a shift pattern and a splitter auxiliarysection connected in series with said main section, a splitter shiftmechanism for automatically implementing splitter shifts and acontroller for receiving input signals indicative of system operatingconditions and for processing same according to predetermined logicrules to issue command output signals to system actuators, includingsaid splitter shift mechanism, wherein said controller includes logicrules for: sensing if an upshift target gear ratio was selected prior toactivation of engine governor control; determining a type of shiftevent; and controlling one of an engine speed and an engine torque toproduce a zero torque condition and place the splitter auxiliary sectionin a splitter-neutral condition in response to a positive sensing thatan upshift target gear ratio was selected prior to activation of theengine governor control.
 11. The system of claim 10, wherein the zerotorque condition is produced by controlling a supply of fuel to theengine to increase one of the engine speed and the engine torque. 12.The system of claim 10, wherein the zero torque condition is produced byoverriding the engine governor control.
 13. The system of claim 10,wherein said controller commands the splitter auxiliary section to beautomatically engaged in the upshift target gear ratio when the type ofshift event comprises a splitter upshift event.
 14. The system of claim10, wherein said controller permits a the splitter auxiliary section tobe manually engaged in the upshift target gear ratio when the type ofshift event comprises a compound upshift event.